Indicating apparatus



June 26, 1945; A. E DODD 2,379,219

INDICATING APPARATUS Filed Nov. 20, 1943 B212 E512 E43 I 6 l @a 'i H12;- f I L B ai?? ab? 61;?

Fly. Z.

vuwENToR HIS ATTORNEY Patented June 26, 1945 UNITED y STATES PATENTOFFICE INDICATING APPARATUS Arthur E. Dodd, Edgewood, Pa., assignertog-The Union Switch & ISignal Company, Swissvale, Pa., a corporation ofPennsylvania Application November 20, 1943, Serial No."511,069

3 Claims.

My invention relates to indicating apparatus, and particularly toapparatus in which an indicating device is operated momentarily inresponse to a change in a given condition.

In apparatus in which an indicating device is operated for a briefperiod of time by means of the charging current for a condenser, it isdesirable, for best results, that in preparation for each such operationthe condenser should be discharged as completely as possible.

Onel feature of my invention is the provision of means comprising alcircuit of very low resistance closed for a brief period of time fordis'- charging a condenser in indicating apparatus in which the chargingcurrent for the condenser is employed for operating an indicatingdevice.

I shall describe two forms of apparatus embodying my invention, andshall then point out the novel features thereof in claims.

In the accompanying drawing, Fig. 1 is a dia- J a diagrammatic viewshowing a modification .of

the arrangement of Fig. 1 including an asymemetric unit in series withthe indicating device.

Similar reference vcharacters refer to similarl parts in each of theviews.

Referring first to Fig. 1, a stretch of railway track is shown dividedby insulated joints I into sections 2T, 3T and 4T. Each of the sections2T, 3T and 4T is provided with a track circuit including a battery 5connected across the rails adjacent one end of the section, andincluding a track relay designated by reference character 2R, 3R or 4R,respectively, connected across the rails adjacent the opposite end ofthe section.

As shown in the drawing, section 4T is occupied by a car or train 4N,and hence relay 4R is deenergized; section 3T is unoccupied, and hencerelay SR. is energized; and a car or train 2N is just entering section2T, and relay 2R is therefore just ,changing from the energized to thedeenergized position.

Each of the track relays is equipped with a movable contact elementcomprising a iiexible upper finger 6a and a exible lower finger 6b. Theenergized position of the contact element of each of these relays is asshown for relay 3R. Since contactnger Ba of relay 3R. bears against itsfront contact point it is bent bythe """mtact pressure, 'whereas Contactfinger Bbfis out of engagement with its back 'cnt'ctpoint and istherefore not bent 'The :deenergi'zed fie's'itiii ei the 'contactelement 'of 'each f the relays "isfas shown for relay 4R. Contacthger 6d"of relay 4R is out of yen.';ttge`iii'ent"iifitiiits front y'poiijit'riti is therefore straight because the front contact pressure isrelieved, Whereas contact'iingrb ef relay an is iii engagement with itsbei'ifee'ii'- tact peint and 'isv 'therefore slightly tent. when thecondition of any one of these relaysis changedfrom deenergized toenergized, d'r y'from energized to deener'gized as lsli'o'wr'i for relay2R, its contact linger `6ay is in engagement `with `'its front eeiitattpeint for e brief period wiiiie ite vcontact finger 6i;isine'njgageinent Vwith its back Atentati, peint. vDuring 'this briefperiod, e. tranen path is desea freie tiijr nent teilt-att p'iiit,through `fiiig'er sa, iingeigvvsb, and trie 'baer' teint, forydischarging a high-capacity ereetroiytie condenser C.

An indicating devi-ee, 'eiitwri eee Ben i, is etsii'- nected in acircuit in series with cn'denserC and a suitable 'source bf current,'Sutri foi ex; ampleas a battery Q. f

In Fig. 1a, trie resis't'aiicesjef the variatie parte of the apparatusenewii ifi Fife. i are represented by resistors designate-d by thereference v"entiraeter 1j' fouow'ed by the igereriiee. character fdr thecorresponding part. The i'nt'eriiai lresistente of battery Q istherefore shown as a resistor 1Q; the combined resistances of conductors1, 8a, and 9a of Fig; 1 are shown as a resistor r'l-Ba-Sa; theresistance of bell B is shown as a resistor TB; the combined resistancesof conductors 8 and 9 and the internal resistance of condenser C areshown as a resistor rC-8-9; and the combined resistances of conductors8b and 9b and a contact element Gaf- Gb are shown as a resistor rfi-Bb-Sb.

Condenser C is normally charged to the potential of the current sourceQ, and therefore only the leakage current of the condenser normallyiiows through the winding of bell B in a circuit passing from battery Q,through con? ductor 1, Winding of bell B. conductors 8a and 8, condenserC, and conductors 9 and 9a back to battery Q.

Whenever one of the contact elements Git- 6b bridges, for a brief periodits front and back contact points, when a corresponding relay becomesenergized or deenergized, condenser C becomes discharged over a circuitpath, such for example as the one shown closed by Contact elementlia-lib ofrelay 2R, passing from condenser C,

C, the circuit previously traced through bellB will start charging thecondenser. Thecharging current now flowing will operate bell B'. If thisbell is of the single stroke. type, vthe charging current, upon startingto ilow,wi11 operate bell B to pick up a plunger which strikes a gong.When condenser C has become charged, the plunger will drop back to itsdeenergizedpo/sition. The resist4 ance rB of the bell B is fairly large,and hence resistances TQ and r'l-Bw-Sa may also have considerablevalue'without greatly reducing the charging current for condenser C.

Referring now to Fig; 2, a' modification of the arrangement of Fig. 1 ishere shown, in which al full wave rectifier F, comprising asymmetricunits fl, f2, f3 and f4,connected across terminals X and Y of asuitablealternating current supply, is used instead of battery Q, shown in Fig.1, as the'source of current. A'variable load L is also energized bycurrent from rectier F. If load L had only inductance or resistance, theAaverage voltage supplied by rectifier F across load L, if condenser Cwere not present, would be considerably lower than the peak voltagesupplied by rectifier F. The condenser C provides appreciable ltering ofthe rectier output when load L becomes light or is removed entirely, andmay cause the average voltage across the load L to rise to almost thepeak voltage' of the rectifier. In cases where such a variation inaverage voltage across load L is'undesirable, a blocking rectier Gr maybe connected between load L and condenser C in' order to prevent thecondenser C from'flltering the entire rectiiier`v output.v Withoutrectifier G, the reversal of current ow through bell B, due to theltering action of condenser C,`mi'ght also adversely aect the operation.of bell'B.`

Although the internalresistance TQ of the battery `Q shown in Fig. 1 maybe very low, the corresponding internal resistance rof a recti'flerw'F,

shown in Fig. 2, may be considerable, but the operation of the apparatusin both instances will be entirely satisfactory.

Although I have herein shown and described only two forms of indicatingapparatus embodying my invention, it is understood that various changesand modifications may be made therein within the scope of the appendedclaims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is: p

1. In-indicating apparatus for a stretch of railway track includingan'indicating device and a source of current and also a condenser, thecombination comprising, a circuit for charging said and a trafllcresponsive contact for discharging said condenser while said contact isclosed mornentarily when a train enters said stretch of track and againwhen the train leaves said stretch.

2. In indicating apparatus for a stretch of railway track including anindicating device and a source of current and also a condenser, the com;bination comprising, a circuit including said source of current and saidindicating device and said condenser all in series for chargingsaidcondenser and operating said indicating device, during charging ofsaid condenser, and traffic responsive .means for momentarilydischarging said condenser when a train enters said stretch of track andagain When the train leaves said stretch.

3. In indicating. apparatus for a stretch of rail- Way track includingan indicating device and a source of current and also a condenser and atraflic responsive contact which becomes closed momentarily when a trainenters said stretch of track and also when a train leaves said stretchof track, the combination comprisinga circuit including said source ofcurrent and said indicating device and said condenser all in series forcharging said condenser and operating said indicating device duringcharging of said condenser while said traflic responsive contact isopen, and a branch path including said contact connected across saidcondenser for discharging said condenser while said contact is closed.

ARTHUR E. DODD.

